Programmer’s Guide
3
C4 Commander
Some Useful Terminology
SYSEX
is short for System Exclusive.
This is a MIDI message specific to one
device. The header includes the manufac-
turer's ID and the device ID. A SYSEX message
can be lengthy compared to normal MIDI com-
mands (i.e., MIDI Note or Program Change
messages), because it contains all the data
needed to define the parameters of a device.
Masks
are used to hide or ignore specific se-
lected data in a SYSEX message.
HEX
is short for hexadecimal, a base-16 num-
ber system that represents every byte as two
consecutive hexadecimal digits (e.g., the binary
number 0011 1111 is represented by the HEX
number 3F).
V-Pot
is short for Virtual Potentiometer. These
are the rotary controls on the C4, which are ac-
tually digital encoders but provide the function
of an analog rotary pot.
New Instrument File Creation
What you will need:
Programming experience in XML and C
Familiarity with MIDI SYSEX protocols
An appropriate text editor
Some recommended text editors:
On the PC, use Notepad or WordPad.
On the Mac, use TextEdit.
If you don’t know XML,
STOP RIGHT
HERE
. The assumption here is that you
already have programmming experience;
hence the title “C4 Commander Programmer's
Guide.”
Steps in creating a new Instrument file:
•
Gather the instrument’s SYSEX documen-
tation (see owner’s manual or contact the
synthesizer manufacturer for this informa-
tion).
•
Define masks based on the SYSEX mes-
sages used by the instrument.
•
Define the parameters to be controlled via
SYSEX.
•
Optional — define ValueText messages and
their usage by the instrument.
•
Write the instrument file in a text editor.
•
Test and debug.
C4 Commander XML schema
Each instrument controlled by the C4 must have
an Instrument Definition file. This is a schema
we have created that is used by the C4 to hook
into functions of that instrument. C4 ships with
definitions of many popular instruments.
Since new instruments are being introduced all
the time, there are two options for obtaining
Instrument Definition files. The first is to wait
for someone else to write the definition, and
the second is to write it yourself. If you are im-
patient and wish to give Instrument Definition
writing a try, the following pages will show you
how.
Basics
Since the format for the schema is XML, ap-
propriate start and end tag syntax (<function>
</function>) is required. Failure to do this will
result in errors when the C4 Commander at-
tempts to load your definition file.
Syntax
Please note the use of the “” marks in the In-
strument Definition file’s source code. These
are not Microsoft Word begin/end quotation
marks, as typed above. These are a text editor’s
straight quotation marks like this: " . If you use
a word processor that substitutes open/closed
(curly) quotes instead of the straight quote
marks, it won't translate correctly, and the C4
Commander will return an error message.
